Localization of integrin subunits α6 and β1 during somitogenesis in the long-tailed macaque (M. fascicularis)

The distribution of integrin subunits α6 and β1, and the α6β1 integrin ligand, laminin, was examined during somitogenesis in developmental stages 11, 13, and 16 in the long-tailed macaque, using peroxidase immunocytochemistry. Within differentiating somites in stage 11, α6 expression was observed in the sclerotome, basal surface of dermamyotomal cells adjacent to the basal lamina and on scattered cells throughout the dermamyotome. In further advanced somites in stages 13 and 16, α6 immunoreactivity become restricted to the myotome, α6 was expressed on mesenchymal core cells within the myocele of undifferentiated epitheliod somites and the ventromedial wall of somites commencing differentiation at each stage. β1 distribution resembled that of α6 in stage 11 somitic tissue, however, it remained present on myotome and sclerotome cells in the later stages, and was also expressed on dermatomal cells in stage 16. Laminin immunoreactivity, while more intense and prevalent than α6 and β1 in each stage examined, occurred on the same somite cell populations as the 2 integrin subunits. These results show a defined distribution of α6 on somitic tissue, and suggest this integrin is involved in somite differentiation. They also support a possible role for α6 in myoblast formation and migration. Overlapping of β1 and laminin immunoreactivity with that of α6 further suggests that α6 paris with β1 as a functional heterodimer for laminin in defined somitic regions.